Pump



Oct. 10, 1933.

lill/l B. F. SCHMIDT Filed July 7. 1930 5 Sheets-Sheet 2 By Jiffy Oct.10, 1933. B. F. SCHMIDT` PUMP Filed July 7, 1930 3 Sheets-Sheet 3 pistonto eiect intake and discharge of a liquid piston in its lowermostposition;A

Patented oct. 10, 1933 UNiTED STATES PATENT OFFICE ticularly pertains toa pump of the U PUMP Benjamin F. Schmidt, Los Angeles, Calif.

Application `Iuly 7, 1930. Serial No. 465,835

19 Claims. (Cl. 1031-204) This invention relates to pumps and moreparplunger type embodying a reciprocal piston arranged in a cylinder andoperable on lreciprocation of the or fluid.

An object of the invention is to provide a pump of the above characterin which the contiguous surfaces of the piston and cylinder areprotected against wear due to the presence of sand or other gritty orabrasive particles conta liquid being pumped.

ined in the Another object of this invention is to provide a pump inwhich the liquid being pumped is prevented from contacting the pistonliquid being pumped from during pumping operations.

Another object is to provide a means whereby a uid seal will be aordedbetween a pump piston and the liquid being pumped whereby the latterwill be effectively prevented from passing beand its entween the pistonand its encompassing cylinder.

Another object is to provide a construction in the pump whereby thefluid seal will be maintained in proper relation to the pistonthroughout the stroke thereof, and also whereby the sealing uid will beeiectivelyk confined against escape so as to insure proper functioningthereof for protracted periods.

A further object is to provide a pump which while being of extremelydurable construction, is adapted to be readily repaired and in whichreplacement of parts may be easily acc A further object is to provide ameans in a pump of the above character whereby a body of lubricant maybe maintained between opposing bodies of sealing iluid.

With the foregoing objects in vi with such other objects and advantagesas may omplished.

ew, together subsequently appear, the invention resides in the parts andin the combination, construction and arrangement of parts hereinaftervdescribed and claimed and illustrated by way of ex ample in theaccompanying drawings, in which:-

Fig. 1 is a View in vertical section of the pump illustrating oneembodiment of the invention and showing the partsas arranged wit h thepump Fig. 2 is a sectional view of the pump constructed as shown in Fig.1, illustrating the piston in its uppermost position;

Fig. 3 is a view in cross section taken on the line 3--3 of Fig. 1;

Fig. 4 is a view in cross section as seen on the line 4 4 of Fig. 1;

Fig. "5 is a view in section taken on the line 5*--5 lof Fig. 1;

Fig. 6 is a view in vertical section of the pump 65 illustrating another-form of the invention;

Fig. 7 is a view in cross section as seen on the line '7-7 of Fig. 6;

Fig. 8 is a view in cross section taken on the line 8 8 of Fig. 6. Y y

Fig. 9 `is a View in Vertical section of a pump showing anotherembodiment of the invention;

Fig. 10 is a view in cross section as seen on the line 10'-10' of Fig.9; i

Fig. 11 is a view in vertical section depicting 75 a further modied formof pump construction embodying the invention;

Fig. 12 is a view in section and elevation of the upper portion of thepump shown in Fig. l1, illustrating the parts disposed in an alternativeposi- 80 tion;

Fig. 13 is a view in cross section and plan as seen on the line 13 ofFig. 11;

Fig. 14 is a view in cross section taken on thel line 14-14v of Fig. 12;

Figs. 15 and 16 are details in cross section showing the piston as ttedwith a cup leather and a piston ring, respectively.

In the form of the invention shown in Figs. 1 to 5 inclusive, a pumpcyunder A is provided 90 in which is mounted a reciprocal piston B; thecylinder A being connected at its upper end to a tube C leading todischarge and being tted at its lower end with a tapered plug 16 formedwith an opening 17 constitutinga liquid or fluid in- 95 take and whichis designed to be submerged in the liquid or fluid to'be pumped. Thepiston B is tubular, is open at its lower end to the cylinder A and hasits'upper end equipped with a cap 18 to which is afixed a pump rod 19through which the piston is reciprocated from any suitable source ofpower. The cap 18 is formed with openings 20 which aord an outletcommunication between the interior of the pump cylinder A above 105 thepiston and a valve chamber 2l carried by the piston and equipped with anormally closed valve 22 here shown as comprising a ball which'normallygravitates to a seated position on the margin of an opening 23 formed inthe bottom 110 of the valve chamber 21 and leading to the interior ofthe piston. 7

Connecting with the intake opening 17 and leading upwardly within thepiston B in telescoped and spaced relation thereto, is a tube 24, 'theupper end of which is fltted with a normally closed valve 425 here shownas comprising a ball which normally gravitates to a seated position on avalve seat 26 whereby the upper end of the tube 24 is normallymaintained closed to the interior of the piston B.. The ball valve 25 isconfined within a cage 27 to maintain it at all times in operativerelation to its seat.

The piston B is formed with an enlarged lower end portion indicated at28, and a reduced upper end portion 29; the lower end portion 28 havingits outer periphery formed to extend proximate to and to effect slidablecontact with the inner periphery of the cylinder A and the upper reducedportion 29 being' formed to extend in spaced concentric relation to theinner periphery of the cylinder A to afford a clearance space 30 inwhich is disposed a quantity of liquid as indicated at 31, and whichliquid constitutes a sealing fluid above the enlarged lower end portionof `the piston. The body of sealing fluid thus surrounds the upperportion of the piston and is extended such distance longitudinally ofthe pis-1 ton as to afford a substantial depth thereof. This sealingfluid may comprise any suitable lubricating fluid of greater specificgravity than the liquid to be pumped and not soluble therein, and mayconsist, for example, of mercury. In some instances the sealing fluidmay consist of an oil, or it may comprise water, according to thecharacter of liquid or fluid to be pumped. The interiorn of the piston Balso contains a quantity of the sealing fluid as indicated at 32, whichwhen the piston is in its lowermost position as shown in Fig. 1, has itssurface level disposed on a plane spaced above the plane of the topsurface of' the fluid body 31 ,exteriorly ofthe piston. The body ofsealing fluid 32 affords a seal beneath the piston and lls the spacewithin the cylinder A, below the piston when the latter is in itsuppermost position as shown in Fig. 2 and also extends part way into thelower portion of the piston so that the lower edge of the latter will bealways submerged in the sealing fluid. The bodies 3l and 32 of thesealing fluid thus extended on opposite sides of the enlarged portion 28of the piston and collectively form a body of fluid which is trapped orconfined in the cylinder A, and in which the piston works.

The piston portion is constructed to have a close sliding contact withthe walls of the cylinder A, and accordingly such space as occursbetween the piston and its accompanying cylinder is very slight andrestricted so that a.` free ow of 'the sealing fluid from one side ofthe piston to the other during reciprocation thereof, is prevented, andwhereby as the piston moves up and down the column of sealing fluidexteriorly of the piston will move substantially coincident therewith.Ordinarily this sliding contact between the piston and cylinder is suchasV to obviate the use of mechanical packing piston rings, cup leatherand the like-but inl some instances it may bedesirable to providegreater clearance between the piston and cylinder and to then provide apacking ring such as a cup leather a as shown in Fig. 15 or a pistonring b as shown in Fig. 16. Inasmuch as some of the sealing fluid abovethe piston may slowly work downwardly past the piston and be added tothe column of sealing fluid `being equal.

interiorly of the piston means are provided for compensating for suchdisplaced sealing fluid. This means is shown in Figs. 1 and 2 ascomprising a duct 33 carried. by the piston, which duct opens at itslower end to the interior of the piston adjacent the lower end thereofand thus communicates with the interior of the casing A below thepiston. The upper end of the duct 33 opens through a port 34 to thespace 30 above the body 31 of ,the sealing fluid thus affording acommunication between the duct and the interior of the casing A abovethe enlarged portion of the piston and in spaced relation thereto. Theport 34 serves to establish the head of the column of the sealingfluidainteriorly of the piston. An upwardly opening check valve 35 isprovided in the upper end portion of the fduct 33 and is adapted vtonormally close the duct against ingress of fluid to the duct from thepump cylinder above the piston.

In initially assembling the pump, such quantity of the sealing fluid isplaced therein that when the piston is in its lowermost position asshown in Fig. 1, the level of the sealing fluid within the mainsubmerged in the sealing fluid as shown in Fig. 2.

By the construction shown in Fig. 1, the valve 22 and 25are arrangedcomparatively close together when the piston is in its lowermostposition which is desirable where the pump is employed in pumping gasesto minimizethe quantity of gas confined in the pump below the valve 22.

In the operation of the form of the invention just described, assumingtheA pump to be positioned in a body of the liquid or fluid to bepumped, upward movement of the piston will induct liquid or fluidthrough the pump inlet 17, and through the tube 24, past the valve 25and into the space within the piston above the sealing fluid, andbeneath the valve 22. The pump piston in moving upwardly, carries thebody 31 of the sealing fluid therewith and also raises such column ofthe fluid being pumped as may be 'contained within the pump 'casingabove the piston by reason of the valve 22 being closed. On down strokeof the piston, the liquid or fluid previously delivered into the spaceabove the sealing fluid within the piston being entrapped therein by thevalve 25, will be caused to pass above the piston by flowing past thevalve 22 in the manner common in the operation of reciprocalw pumps.

The'piston B, in moving downwardly, displaces the sealing fluidtherebeneath, which displaced sealing fluid will be confined within andbeneath the piston, it being prevented from passing the exterior of thepiston by reason of the restriction .of the clearance space between thepiston and the pump cylinder andalso by reason of the pressures on thecolumns 3l and 32 of the sealing fluid then In event the volume of thecolumn of sealing fluid 32 be increased by the addition theretoof aportion of the body of sealing fluid 31which might occur during upstrokeof the piston, such increase will, when the piston reaches itsylowermost position, cause an increase in the height of the column ofthe sealing`fluid inthe duct 33,

thereby eifecting opening of the check valve and thereby permitting aquantity of the sealing fluid to discharge from the duct through theport 34 into the space 30 until the level of the column 32 of thesealing fluid falls suiciently to permit the valve 35 to resume itsseat. The valve 351s of such character as to oat to its open position inthe sealing fluid and to gravitate to its closed position.

In the form of the invention illustrated in Figs. 6, 7, and 8, to whichreference is now had, the pump includes a cylindrical casing D and areciprocal piston E carried on a rod F; the piston E being cylindricaland of uniform outside diameter throughout its length and the pumpcylinder being formed with aireduced internal diameter at its lower endsuch that when the piston is in its lowermost position, the lowerportion of the piston will slidably contact the inner periphery of thepump cylinder and the upper portion of the piston will be spaced fromthe inner periphery of the pump cylinder `to provide a chamber 36 inwhich is placed a body of sealing uid.

The lower end of the pump cylinder is closed by a plug 38 formed with acentral intake opening 39 from which projects upwardly into' the tubularpistona tube 40, the lower portion of which is equipped with a footvalve 41. This construction permits the use of a large foot valve wheredesired. The upper portion of the piston is provided with a normallyclosed, upwardly opening valve 42.

A column of sealing fluid 43 is provided within the piston and lowerportion of the pump cylinder the normal level of which, when the pistonis in its lowermost position, is above that of the sealing `fluidexteriorly of the piston. As a means for maintaining an establishedrelation between the bodies 37 and 43 of the sealing fluid, the pumpcylinder is formed with a duct 44, the lower'end of which opens to theinterior of the cylinder be: neath the piston E and the upper end ofwhich opens to the space 36 through a normally closed check valve 45,which valve is normally maintained in a seated position under the urgeof a spring 46 and which spring serves to hold the valve 45 againstfloating in the sealing uid. The spring 46 is of such strength as toprevent iioating of the valve, yet to permit the valve being liftedwhenA the column of sealing uidinternally .of the pistonexceeds theheight of the column of the sealing-fluid externally of the piston.

The operation of the pump thus constructed,

is substantially the same as that described with` reference to the formof the invention shown in Fig. 1, excepting that the maintenance of thebody of the sealing uid 37 exteriorly of the piston is maintainedthrough the duct 44 in the pump cylinder wall instead of through v aduct carried by the piston.

and 10, the pump comprises a pump cylinder G having a reduced lower endportion H in which is reciprocably mounted a piston I having its lowerportion slidably contacting the pump cylinder portion H and having itsupper portion spaced from the pump cylinder to provide a` space 47 inwhich is disposed a body of sealing fluid 48. The lower end of the pumpcylinder is tted with a plug 49 having a central opening 50 formed withan inclined wall on which is loosely seated a tube 51 formed with anintake 52 tted with a foot valve 53 and which tube is positioned withina tube 54 afxed to the plug 49 and extended upwardly into the tubularpiston H. A body of sealing uid 55 is provided within the lower endportion of the pump cylinder and extends around the tube 54 and withinand beneath the piston I, the level ofwhich fluid normally extends tothe level of the body 48 of the sealing uid when the piston I is in itslowermost position. Carried by the piston I is a duct 56, the lower endof which opens adjacent the lower end of the piston and the upper end ofwhich communicates through a port 57 with the` space 47 through anormally closed check Valve 58; the

valve being normally maintained in its seated position under urge of aspring 59.

The piston I is carried on a pump rod J and is iitted at its upper endportions with an upwardly opening valve 60 and connecting with thepiston is a'stem 61 which projects downwardly through the tube 54 andinto the tube 51; the lower end of the stem 61 being provided with aange 62 which is adapted on upward movement of the piston I to a pointbeyond the termination of its upstroke to ,eifect engagement with theupper end of the tube 51 whereby the latter with its valve 53 may belifted from the pump on 1 withdrawing the piston I from the pumpcylinder. The upper end of the tube 51 is formed with openings 63affording a communication between the tubes 5,1 and 54.

The pump as shown in Fig. 9, operates in substantially the same manneras that previously described, but by the construction and arrangementshown in Fig. 9, the foot valve 53 is rendered removable from the pumpcasing on withdrawing the piston from the latter. In this constructionthe tube 54 being securely attached to the plug 49 serves to entrap the-sealing Iiuid within the pump cylinder when the piston is removed fromthe pump casing. After the piston has been removed, it may be replacedby merely lowering it in the casing to its lowermo'st position,whereupon the sealing iiuidl will seek its proper levels.

Where the clearance space between the piston and cylinder is provided inthe cylinder wall as shown in Figs. 6 and. 9 the column of the cylinderfluid exteriorly of the piston extends to a height greater than thelength of the piston stroke to prevent the portion of the piston, whichslidably contacts the cylinder when the piston is in its lowermostposition, from being exposed to the liquid being pumped kwhen the pistonis in its uppermost positionthus insuring against any grit being carriedby the piston through the sealing fluid and into the joint between thepiston and its cylinder.

In the construction shown in Figs. 6 and 9, the piston moves relativelyto the outer column of the sealing uid as distinguished from that shownin Fig. 1 in which the outer column of the ,i sealing uid moves with thepiston and rela- In the form of the invention shown in Figs.9

tively to the cylinder; `the column of fluid around the piston in thelatter instance being of a height greater than the length of the pistonstroke so that the surface of the piston contiguous the cylinder wallswill not overlie on the upstroke of the piston `any portion of thecylinder which has been ex- In the construction shown in Figs. 11, 12,13,

well casing. In this instance the well casing indicated at K is formedat its lower endl portion with a tapered seat 65 surrounding an inlet 66and the pump is formed with a pump cylinder L having a tapered lower endportion 67 adapted to seat on and effect close connection with thetapered inner surface of the seat 65. The pump cylinder is designed tobe lowered into the well casing and to be demountably secured theretoand as a means for efectuating a connection be-Y tween the pump cylinderand the well casing the latter is formed with an inwardly projectingflange 68y which is inclined on its upper and lower surfaces and mountedon the pump cylinder is a series vof radially slidable catches 69adapted to be moved in and out of engagement with the under side of theflange 68, and arranged in the upper portion of the pump cylinder inslidable, telescoping relation thereto, is a sleeve 70 having a taperedlower end 71 adapted to effect wedge engagement with the slide catches69 to force the latter outwardly into engagement with the under side ofthe flange 68 as shown in Fig. 11. The catches 69 are here shown ascomprising circular discs formed with transverse slots c and engagingthe slots is a split, resilient ring d which serves to hold the catchesin place. The sleeve 70 is formed with a collar 72 projecting beneath aninturned projection 73 on the upper end portion of the pump cylinder;the collar 72 being adapted to engage said projection 73 on lifting saidsleeve '70.

A tubular stem 74 is connectedto the upper end of the sleeve 70 andleads to discharge at a suitable point in the well casing and throughwhich projects a pump rod 75 connegted at its lower end to a pump pistonM which latter is here shown as constructed in the manner disclosed inFig. 1, being formed with an enlarged lower end portion 76 whichslidably contacts the pump cylinder L and has a reduced upper endportion to provide a space 77 in which is placed a sealing fiuid 78. Atube 79 is carried by the lower end of i the pump cylinder and projectsupwardly within.,

the piston with its lower end opening to the intake 66 and with itsupper end fitted with upwardly opening foot valve 80. The upper endportion of the piston M is equipped with an upwardly opening valve 81and the lower portion of the piston is fitted with a by-pass duct 8 2affording a communication between the lower portion of the piston andthe space 77. The pump mechanism in this instance operates in the samemanner as that previously `describedwith reference toFig. 1.

In assembling the pump shown/in Fig. 1'1, the

vpump cylinder L issuspended from the tube 74 as shown in Fig. 12, andlowered into the well casing until the lower end thereof seats on thelower end of the well casing, whereupon the slide catches 69 arepositioned to extend beneath'the flange 68 so that von further loweringof the stem 74 relatively to the pump cylinder, the tapered lower end 71thereof will act to force the slide catches into engagement with thewell casing as shown in Fig. 11. ated as before described. When it isdesired to remove the pump from the well casing, the ,stem 74 iswithdrawn thereby moving the collar 72 into engagement with theprojection73 and the tapered end portion 71 re-disconnected relativelyto the slide catches 69 so that on effecting an upward pull on the pumpcylinder, the slide catches 69 will ride inwardly out of engagement withthe The pump may then be operfiange 68, whereupon the pump cylinder maybe withdrawn from the well casing. The weight of the sleeve 70 andtubular stem 74 acts to maintain the tapered end of the sleeve in wedgeengagement with the catches 69.

An important feature of the invention derived from the construction ofthe piston and the arrangement of the sealing fluid as set forth is themaintenance at all times throughout the reciprocal movement of thepiston of a film of the sealing fluid in such clearance space or spacesas may occur or be present between the outer periphery of the lower endportion of the piston and the contiguous inner periphery of the pumpcylinder, which serves to effect lubrication of the wearing -surfaces.of the piston and cylinder and which coupled with the provision of asubstantial body ofthe sealing fluid both above and below the proximatesurfaces of the piston and cylinder, insures against any liquid or iiuidbeing pmnped from passing from one side of the piston to the other.

It will be noted that in the several applications of the invention, ashere shown, the pump piston is maintained in a fluid seal throughout itsstroke; and that the sealing fluid is so entrapped as to prevent itsescape from the pump.

It -will also be observed that in each of the pumps shown I haveprovided a pump cylinder equipped with a piston and a standing intakefitted with a foot Valve, in which the piston and the standing intakeare surrounded by a sealing fluid of a specific gravity greater than thefluid being pumped, and insoluble therein and to such heighth or depththat the substance being pumped will be prevented from contacting thesurfaces of the piston or the cylinder which contact each other duringpumping operations; and that I also provide a means for maintaining thebodies of sealing fluid above and below the piston at'predetermined andconstant levels in relation to each other. M

By the provision of the upstanding intake tube, equipped with the footvalve, with the intake tube opening above the column of sealing fluid,loss of the sealing fluid through the-intake is prevented, and passingof the liquid being pumped through the sealing fluid is obviated andconsequent emulsication of the sealing uid is prevented.

In some instances it may be desirable to afford lubrication of thepiston and cylinder other than will be effected by the sealing fiuid.This may be accomplished by the provision of spaces e and f bodied inthe pump as a. sealing fluid, its funcf tion is not limited to a sealingaction as the bodies of this fluid serves primarily as a shield orbarrier to protect the contiguous surfaces of the piston and cylinderagainst the passage of grit. The fluid also acts to displace liquid orfluid being pumped and further serves as a lubricant.

A pump constructed to embody the invention is applicable to many uses,but is especiallysuitable for use in pumps employed in pumping liquidscontaining solid particles of abrasive character as the fluid seal willfloat the solids and prevent their working past the piston. However, thepump may be employed in pumping various liquids, and may be used inpumping gases. f

It is to be understood that the manner of carrying the invention intoeffect is herein specifically set forth to enable those skilled in theart to make and use the same and is to be considered as illustrative andnot in a limiting sense; and that various changes may be made in theparts and in their construction and arrangementrwithin the meaning ofthe terms and scope of the appended claims without departing from thespirit of the invention.

I claim:

1. In a pump, a pump cylinder, a reciprocal piston therein, a body offiuid on each side of said piston arranged to prevent a liquid beingpumped from contacting adjacent slidably contacting surfaces of saidcylinder and piston, an upwardly extending intake tube in the pumpcylinder projecting above the body 'of iiuid below said piston, a valvein said tube, said iiuid being of greater density than a liquid to bepumped, and valve controlled means for maintaining said bodies of fluidin relatively proportional volumes on each side of said piston. l

2. In a pump, a pump cylinder, a reciprocal piston therein, `having aportion thereof slidably contacting said cylinder, a iiuid in saidcylinderl eifecting a seal immediately above and below,r the slidablycontacting portions of said piston and' cylinder and affording a film ofthe iiuid between the piston and cylinder, an upwardly extending intaketube in the pump cylinder projecting above the'body of fluid below saidpiston, avalve in said tube, and valve controlled means for effectingdelivery of saidrfluid from below said slidablycontacting portionstoabove said portionsaw 3. In a pump, a pump cylinder, a verticallyreciprocal piston therein, there being a clearance space affording aworking t between said piston and cylinder, a shielding fluid entrappedin saidcylinder at each end of said clearance space and lling saidspace, an upwardly extending intake tube in the pump cylinder projectingabove the body of fluid below said piston, a valve in said tube, andvalve controlled means for maintaining said uid in substantiallyrelativeproportions of volume at each end of said space.

4. In a pump, a pump cylinder, a vertically reciprocal piston thereinhaving a lower end portion slidably contacting said cylinder, a chamberbetween the upper portion of said piston and said cylinder, a sealingfluid in said chamber adapted to ow downwardly between said piston andcylinder, a column of sling uid-in said cylinder beneath said piston inwhich the lower portion of said piston is submerged throughout thestroke of the piston, an upwardly extending intake tube in the pumpcylinder projecting above the body of fluid below said piston,a valve insaid tube, and valve controlled means for eiecting delivery'of uid fromsaid columnthereof to said chamber.

5. In a pump, a pump cylinder, a vertically reciprocal piston thereinthe lower portion of which extends contiguous the walls of said cylinderand the upper portion of which is spaced from said cylinder, a sealingfluid in the space between said piston and cylinder, said piston beingtubular and open at its lower end to said cylinder, a. column of sealingiiuid in said cylinder extending internally of said piston, means forconveying pumped uid from beneath said column of sealing uid to a pointthereabove, a duct carried by said piston leading from the lower portionof said piston in open communication with said cylinder beneath' thepiston and communicating with the umn of sealing fluid entrapped beneathsaid piston, a duct formed in the cylinder wall affording acommunication between the interior of the cylinder beneath the pistonand the chamber extending between the cylinder and piston, and anormally closed check valve in said duct.

7. In a pump, a pump cylinder having an intake at the lower end thereof,a tube leading from said intake and extending into the pump cylinder inspaced relation thereto, said tube forming a communication between thepump intake and the pump cylinder, a foot valve in said communication, atubular piston in said pump cylinder having its lower end inopencommunication with said cylinder and being arranged in telescoped,spaced relation to said tube, a passage leading from the interior rofthe upper portion-of said piston to said pumpv cylinder, an upwardlyopening valve in said passage, va column of liquid entrapped in saidpump cylinder extending upwardly in said piston in which the lowerportion of said piston travels throughout the length of stroke'of thepiston, a second body of liquid surrounding the upper portion of saidpiston apart from the aforesaid column of liquid, a duct leading fromsaid column of liquid to said body of liquid, and an upwardly openingcheck valve in said duct.

8. In a pump, a pump cylinder having an intake at its lower en'd, areciprocal tubular piston in said cylinder having an open lower end, atube connected to said intakeand extending upwardly in said cylinder andwithin said piston, a valve housing demountably seated in said tube, afoot valve in said housing, a connection between said piston and saidvalve housing for effecting the removal of said housing and Valve onwithdrawing said piston from said pump cylinder, a column of liquidsurrounding said tube interiorlyy of said piston, a column of liquidsurrounding said piston apart from the column of liquid invlteriorlythereof, a duct through which liquid may be delivered from the column ofliquid interiorly of the piston to the column exteriorly thereof andacheck valve for preventing back ow of liquidfrom the exterior of saidpiston to the interior thereof.

9. In a pump, a well casing having an intake, a pump cylinderdemountably arranged in said casing having an intake arranged tocommunicate with the well casing intake, means for detachably connectingsaid pump cylinder and well casing, a reciprocal piston in said pumpcylinder open at its lower end, a tube leading from the pump cylinderintake into said piston, affording a communication between the pumpintake and the interior of the piston, a foot valve in saidcommunication, a valve controlled passage leading from the upper portionof said piston, a column of liquid extending interiorly f the pistonrelatively to which said piston is movable and in which the lowerinterior portion of the piston is submerged, a body of liquidencompassing the upper portion of the piston apart from said column ofliquid, and means operable on down stroke of piston to effect deliveryof liquid from said column interiorly of the piston to the body of.liquid exteriorly thereof.

10. The structure called for in claim 1 including a lubricant traparranged between contiguous surfaces of the cylinder` and piston forcontaining a lubricant of less density than the bodies of fluid on eachside of the piston. i

11. The structure called for in claim 1 in which the piston is formedwith a reduced portion for the reception of a lubricant arranged toafford a body of lubricant between the bodies of fiuid on the oppositesides of the piston.

12. In a pump, a pump cylinder, a reciprocal piston therein, bodies ofmercury extending above and below said piston and arranged to afford ashield between the piston and cylinder against a. fluid being pumpedfrom contacting the surfaces of the cylinder and piston which arecontiguous throughout the length of stroke of the latter, and means forretaining a body of lubricant interposed between the piston and cylinderand between the bodies of uid above and below contacting portions ofsaid piston and cylinder.

13. In a pump, a pump cylinder, a hollow reciprocable piston therein, anupwardly extending intake tube in said cylinder projecting interiorly ofsaid piston, a valve associated with said tube, a body of protectivefluid interiorly of said piston surrounding said tube, a second body ofprotec- `tive fluid exteriorly of said piston, means associated withsaid piston and cylinder separating said uid bodies into independentcolumns through which restricted leakage of fluid from one column to theother in one direction may occur, and means for maintaining said fluidbodies in constant proportional volumes during reciprocationof saidpiston to compensate for such leakage.

14. In a pump having a barrel and a plunger slidably contacting saidbarrel, independently en' trapped bodies of protective fluid confinedabove and below the contactingsurfaces of said plunger and barrel, andmeans for automatically delivering iiuid from one body of saidprotective uid to the other to compensate for leakage past thecontacting surfaces of said plunger and barrel and to maintain saidbodies of protective fluid in constant proportional volumes, and meansfor conveying pumped fluid from beneath the body of sealing uid belowsaid contacting surfaces to a point above said body of fluid independentof said body of fluid.

15. In a pump, a barrel, a piston therein, independently entrappedcolumns of protective fluid in which the working surfaces of said pistonand barrel are immersed, means for maintaining said columns ofprotective uid at predetermined levels relative vto said workingsurfaces, and means for conveying pumped iiuid from beneath said columnsof protective fluid to a point above said columns of fluid aparttherefrom.

16. In a pump, a barrel, an upstanding valved intake tube in saidbarrel, a tubular piston telescoping said tube, independently entrappedcolumns of protective iiuid disposed interiorly and exteriorly of saidpiston and immersing the working surfaces of said piston and barre1,saidprotective fluid being insoluble in the uid to be pumped, and means formaintaining said columns at predetermined levels relative to saidworking surfaces.

17. In a pump, a barrel, an upstanding valved intake tube in saidbarrel, a ltubular piston telescoping said tube, separate columns ofprotective uid disposed interiorly and exteriorly of said piston andimmersing the working surfaces of said piston and barrel, and means formaintaining said columns at predetermined levels relative to said lworking surfaces, including avalved by-pass per, 100

mitting passage of iluid from the interior column to the exteriorcolumn.

`18. In a pump, a pump cylinder, a reciprocal piston therein having awall portion the outer periphery of said cylinder in slidable relationthereto, said piston also having a reduced portion'extending above saidwall portion forming a space for the reception of a iiuid; a body ofVperipheryof which extends proximate the inner fluid entrapped in saidcylinder above said wall 11g portion, a body ofv fluid entrapped in saidcylinder below said wall portion, means for conveying pumped liquid oruid from beneath said last named body of fluid to a point thereaboveapart therefrom, said bodies of fluid being of greater density than theliquid or fluid to be pumped, and means for maintaining said bodies offluid in definite 'relative proportions of volume during 'reciprocationof said piston.

